A number of medical diagnostic instruments are known that allow inspections of body cavities with minimal invasiveness of a patient. An otoscope, for example, is used for examining the interior of the ear canal and includes an elongated body portion and a depending handle portion. The body portion includes an distal frusto-conical insertion portion which is sized for placement within the ear canal. An imaging system, such as a rod lens assembly, located within the insertion portion focuses an optical image of a target for viewing through a proximally located eyepiece portion.
More recently, otoscopes, as well as other medical diagnostic instruments, have been configured to allow the positioning of a miniature video camera, including a solid-state imager such as a CCD, CMOS, or other similar device which converts an optical image from a focusing lens system into electrical signals for transmission. The transmitted electrical signals are then often converted into a monitor-ready video signal format (PAL, NTSC, SECAM etc.) for display on a peripheral device, such as a video monitor. To that end, instruments are also known in which the video camera can be positioned as a proximal attachment essentially replacing the eyepiece portion, such as described in U.S. Pat. No. 5,363,839 issued to Lankford, and U.S. Pat. No. 5,239,984 issued to Cane et al, among others. Alternately, a miniature video camera can be positioned in the distal end of the instrument, such as described in commonly assigned and copending U.S. patent application Ser. No. 08/818,422 to Monroe, et al., and U.S. Pat. No. 5,379,756 issued to Pileski. In each instance, the target of interest is illuminated using a plurality of optical fibers arranged or otherwise adjacent the tip opening of the distal insertion portion. The source of illumination can be a halogen lamp provided within the handle portion, such as described in U.S. Pat. No. 5,239,984, or an externally disposed light box, as is commonly known.
Another commonly known medical diagnostic instrument is a skin surface microscope (also commonly referred to as a dermatoscope) used to examine skin disorders, such as moles, warts, lesions, and the like. An increase in the incidence rate of melanomic and other skin cancers has produce a more heightened concern, thereby increasing the need for these examinations.
Typically, a skin surface microscope includes a body portion having a viewing optic having a relatively large diameter (approximately 25 cm) disposed at a distal end thereof. The distal viewing optic includes a measuring reticle to provide a frame of reference relative to the target of interest which is viewed through a proximal eyepiece portion, preferably having at least one magnifying optic. In use, the distal viewing optic is placed in direct contact with a portion of skin surface of interest, and the target is viewed through the eyepiece portion. A videoized version of this instrument is manufactured under the tradename of Video Episcope.TM. by Welch Allyn, Inc. Other similar instruments are manufactured by Heine Instruments, Inc.
As in the case of other diagnostic instruments, illumination is required in order to adequately view the target. Typically, skin surface microscopes include a light source, usually a halogen lamp, contained in the handle and oriented at an acute angle to effectively illuminate the viewing optic and target.
With the minimal amount of space available in a doctor's office there is a general desire to improve the general efficiency therein. Therefore, it would be desirable to allow a physician to be able to use a single diagnostic instrument interchangeably to perform several different examination procedures. There are a number of associated problems, however, which have made the notion of providing a skin surface microscopic attachment for a standard video otoscope difficult to implement. Because the illumination and viewing axes of the video otoscope are substantially collinear, a typical episcopic viewing window would invariably reflect an image of the illuminator into the image as perceived by the viewing optics. In addition, direct illumination also produces glare, from the skin and reticle, making examination ineffective, in either instance, without significant modification of the instrument.
Another problem confronted in the use of skin contacting microscopes occurs in the case of raised skin disorders, such as warts, etc. Typically, physicians use oil in conjunction with the air/skin boundary in order to eliminate surface glare and allow viewing deeper into the skin. A conventional skin contacting optical element used for measuring or observing the disorder is likely to compress the target. There are occasions, however, when the physician may desire to view the disorder in an uncompressed state.